Method for treating cellulose-containing fibers or planar structures containing cellulose-containing fibers

ABSTRACT

Cellulosic substrates are treated with compound(s) containing at least two primary amino groups and compounds containing at least one β-ketocarbonyl group. The substrates exhibit good strength and hand properties.

The invention relates to a method for treating cellulose-containing fibers or planar structures containing cellulose-containing fibers.

US 2004/0118540 A1 describes a papermaking process in which first a high molecular weight amine component having an NH₂ concentration of at least 1.5 meq/g is introduced into the aqueous cellulose fiber mixture. Separately therefrom, a second component which can react with amino groups and which is either a polyanionic compound or an aldehyde-functional polymer is then added.

A paper product having increased strength is claimed in U.S. Pat. No. 6,824,650 B2. The product contains a combination of a polyvinylamine and a complexing agent selected from an aldehyde-functional polymer and a polyelectrolyte. The paper product is strengthened by reaction of polyvinylamine with the complexing agent.

Articles which contain cellulose of which at least part was chemically modified and where a further chemical has formed chemical bonds are claimed in U.S. Pat. No. 6,916,402 B2. The chemical modification of the cellulose can be carried out with compounds which contain aldehyde, epoxy or anhydride groups, while the further chemical then contains amino, thiol, amido, sulfonamide or sulfinic acid groups—or vice versa.

It was the object to provide a method by means of which the wet strength of cellulose-containing products, in particular the wet strength of paper towels, is to be increased, it being intended that the products also have a soft handle. The object is achieved by the invention.

The invention relates to a method for treating cellulose-containing fibers or planar structures containing cellulose-containing fibers with a combination of

(1) compounds having at least two primary amino groups and (2) compounds having at least one β-ketocarbonyl group.

The compounds (1) used in the method according to the invention may have a monomeric, oligomeric or polymeric character. The compounds (1) preferably contain at least five primary amino groups (—NH₂), preferably at least 20 primary amino groups (—NH₂) and particularly preferably at least 100 primary amino groups (—NH₂). The density of amino groups in compounds (1) is preferably at least 1.0 meq/g, preferably at least 3.0 meq/g (meq/g=milliequivalent per g of substance=equivalent per kg of substance).

Polyamines are preferably used as compounds (1). Examples of compounds (1) are polymers of ethyleneimine in linear or branched form and polyvinylamine. The latter obtained by polymerization of N-vinylformamide and subsequent partial or complete hydrolysis are generally commercially available in the form of aqueous dilutions.

The compounds (2) used in the method according to the invention may have a monomeric, oligomeric or polymeric character, preferably a polymeric character. The compounds (2) preferably contain at least two β-keto-carbonyl groups and preferably at least three β-keto-carbonyl groups.

The β-ketocarbonyl groups in compound (2) preferably have the structure of the formula

—Y′—C(O)—CHR⁴—C(O)—CH₂R⁴

or its tautomeric enol form of the formula

—Y′—C(O)—CR⁴═C(CH₂R⁴)—OH

in which

-   Y′ is —O—, —NR²— or

preferably —O—,

-   R² is a hydrogen atom or a monovalent hydrocarbon radical having 1     to 30 C atoms, preferably a hydrogen atom, and -   R⁴ is a hydrogen atom or a monovalent hydrocarbon radical having 1     to 18 C atoms, preferably a hydrogen atom.

In the method according to the invention, β-keto-carbonyl-functional monomeric compounds (2a) of the general formula

L(—Y—C(O)—CHR⁴—C(O)—CH₂R⁴)_(e)  (I)

or their tautomeric enol forms in which

-   e is an integer from 1 to 20, preferably 2 to 20, preferably 2 to 8, -   L is a monomeric organic radical having the valency or functionality     corresponding to the index e in formula (I), i.e. a monofunctional     to 20-functional monomeric organic radical, preferably a     monofunctional to 8-functional monomeric radical, -   Y is —O— or —NR²—, preferably —O—, -   R² is a hydrogen atom or a monovalent hydrocarbon radical having 1     to 30 C atoms, preferably a hydrogen atom, and -   R⁴ is a hydrogen atom or a monovalent hydrocarbon radical having 1     to 18 C atoms, preferably a hydrogen atom,     can be used as compounds (2).

β-Ketocarbonyl-functional monomeric compounds (2a) can be prepared by known methods, preferably by reacting compounds of the general formula

L(—YH)_(e)  (II)

in which L, Y and e have the meaning stated above therefor, with diketenes, diketene-acetone adducts and thermally labile acetoacetates.

The radical L is preferably a hydrocarbon radical which has 1 to 18 carbon atoms and may contain one or more oxygen or nitrogen atoms separate from one another.

Examples of the compounds L(—YH)_(e) of the formula (II) on which the β-ketocarbonyl-functional monomeric compounds (2a) are based are

CH₃OH C₂H₅OH C₄H OH C₃H₅OH (C₂H₅)₂NH C₄H₉NH₂ C₆H₅NHCH₃ HOC₂H₄NH₂ HOC₂H₄NHCH₃ HOC₂H₄OH HOC₃H₆OH CH₃C(CH₂OH)₃ C(CH₂OH)₄ HN(C₂H₄OH)₂ N(C₂H₄OH)₃ N(C₃H₆OH)₃ H₂NC₂H₄NH₂ H₂N(C₂H₄NH)₃H (HOCH₂)₃CCH₂OCH₂C(CH₂OH)₃

Compounds (2) in polymeric form are selected from the group consisting of the

-   -   organosiloxane polymers     -   polyesters     -   polyethers     -   polyacetals     -   polyetheracetals     -   polyesterpolyols     -   polyamides

Compounds (2) may correspond either to only one of these species or may correspond to a combination of two or more species from this group. These in turn may be present in separate compounds and/or may be combined in one polymer type, as is the case with silicone polyethers.

In the method according to the invention, β-keto-carbonyl-functional oligomeric or polymeric compounds (2b) of the general formula

K(—Y—C(O)—CHR⁴—C(O)—CH₂R⁴)_(f)  (III)

or their tautomeric enol forms in which

-   f is an integer from 1 to 10 000, preferably 2 to 2000, preferably 2     to 200, -   K is an oligomeric or polymeric, organic or organo-silicon radical     having the valency or functionality corresponding to the index f in     formula (III), i.e. a monofunctional to 10 000-functional oligomeric     or polymeric, organic or organosilicon radical, and -   Y and R⁴ have the meaning stated above therefor, can therefore be     used as compounds (2).

Examples of the radical K are therefore polymer radicals selected from the groups consisting of the

organopolysiloxanes, polyesters, polyethers, polyacetals, polyetheracetals, polyesterpolyols, polyamides and mixtures and copolymers thereof.

β-Ketocarbonyl-functional polymeric compounds (2b) can be prepared by known methods—analogously to the preparation of the β-ketocarbonyl-functional monomeric compounds (2a)—preferably by reacting compounds of the general formula

K(—YH)_(f)  (IV)

in which K, Y and f have the meanings stated above therefor, with diketenes, diketene-acetone adducts and thermally labile acetoacetates.

Examples of compounds K(—YH)_(f) of the formula (IV) on which the β-ketocarbonyl-functional polymeric compounds (2b) are based are

MeO(C₂H₄O)_(p)H where p=2-20 000

HO(C₂H₄O)_(p)H

HO(C₃H₆O)_(q)H where q=2-200

HO(C₄H₈O)_(q)H

HO-functional polyesters obtained from dicarboxylic acid and diols HO-functional polyesters obtained from dicarboxylic esters and diols HO-functional polyesters obtained from diols and caprolactone

Polyesterpolyols

Partial or complete hydrolysis products of polyvinyl acetate Partial or complete hydrolysis products of polyvinyl-formamide Silicone polyethers obtained from α,ω-dihydroorgano-polysiloxanes and allylpolyethers Silicone polyethers obtained from siloxanes having MeHSiO units and allylpolyethers Polyaminoamides obtained from dicarboxylic acids and diethylenetriamine Polyaminoamides obtained from methyl dicarboxylates and triethylenetetramine Aminosilicones containing H₂NC₃H₆(Me)SiO groups Aminosilicones containing H₂NC₂H₄NHC₃H₆(Me)SiO groups Condensates of polydimethylsiloxanediols and secondary α-aminosilanes, such as cyclohexylaminomethylmethyl-diethoxysilane, Me being a methyl radical.

β-Ketocarbonyl-functional polymeric compounds (2b) are preferably, entirely or at least in proportions, organopolysiloxanes or copolymers containing organo-polysiloxanes, such as silicone polyethers. The organo-polysiloxanes or their copolymers preferably have a linear or branched structure. These polymeric compounds (2b) are prepared by reacting organopolysiloxanes or their copolymers which contain at least two carbinol functions (≡C—OH) and/or primary or secondary SiC-bonded amino groups with the same substances, such as compounds of the general formula (II), i.e. with diketenes, diketene-acetone adducts and thermally labile acetoacetates.

Since the increase in the wet strength of cellulose-containing products is preferably effected in the wet-end region as a result of production, it is advantageous if the organosiloxane polymers used in the method according to the invention are soluble or at least dispersible in water. Organosiloxane polymers having components of relatively high polarity are necessary for this purpose.

In the method according to the invention, β-keto-carbonyl-functional organosilicon compounds (2c) which contain at least one Si-bonded radical of the general formula

or its tautomeric enol forms, where

-   —(Si≡) is the bond to the silicon atom, -   R¹ is a divalent organic radical having 1 to 6 carbon atoms which     may optionally contain nitrogen atoms separate from one another,     preferably a divalent hydrocarbon radical having 1 to 6 C atoms     which may optionally contain one or more nitrogen atoms separate     from one another, -   R³ is a divalent organic radical having 1 to 6 carbon atoms,     preferably having 2 to 6 carbon atoms, preferably a divalent     hydrocarbon radical having 2 to 6 carbon atoms, -   Y, R² and R⁴ have the meanings stated above therefor, -   Z is a divalent to hexavalent organic radical having a monomeric,     oligomeric or polymeric structure, which has a weight-based     heteroatom content of at least 10%, which is bonded via C atoms, -   E¹ is a monofunctional terminal group or an Si—C— bonded radical of     the general formula

-   a is an integer from 1 to 5, preferably 1 or 2, and -   x is 0 or an integer from 1 to 5, preferably 0 or 1, preferably 1,     can as compounds (2) for this purpose.

The β-ketocarbonyl-functional organosilicon compounds (2c) are prepared by a procedure in which,

in a first stage, aminosilicon compounds (i) which contain at least one Si—C-bonded amino group A of the general formula

HNR²—(R³—NH—)_(a)R¹—(Si≡)  (VI)

are reacted with compounds (ii) which contain at least one β-ketocarbonyl-functional radical of the general formula

(E²)_(x)Z-Y—C(O)—CR⁴═C(CH₂R⁴)—OH  (VIIa) or

(E²)_(x)Z-Y—C(O)—CHR⁴—C(O)—CH₂R⁴  (VIIb)

in which organosilicon compounds (2c′) of the general formula

(E²)_(x)Z-Y—C(O)—CR⁴═C(CH₂R⁴)—NR²—(R³—NH—)_(a)R¹—(Si≡)  (V′)

are obtained, in which R¹, R², R³, R⁴, Y, Z, a and x have the meanings stated above therefor, and E² is a monofunctional terminal group or a radical of the general formula —Y—C(O)—CR⁴═C(CH₂R⁴)—OH or —Y—C(O)—CHR⁴— C(O)—CH₂R⁴, and, in a second stage, the organosilicon compounds (2c′) obtained in the first stage are reacted with diketenes (iii) of the general formula

in which R⁴ has the meaning stated above therefor.

In the method according to the invention, the aminosilicon compounds (i) are reacted in a first stage with acetoacetyl compounds (ii) of the tautomeric forms (VIIa) or (VIIb) and are reacted in a subsequent second stage with diketenes (iii). This reaction sequence can be advantageously carried out in a one-pot process. A particularly preferred procedure is the upstream preparation of compound (ii) from the parent compounds (iv) by reacting these with diketenes (iii), after which aminosilicon compounds (i) are metered in at the end of the reaction and the organosilicon compounds (2c) according to the invention are then obtained in a particularly economical method by further metering in of diketenes (iii) after the reaction thereof.

Preferred examples of Si—C-bonded amino groups A of the formula (VI) are

-   -   H₂N—C₂H₄—NH—CH₂—     -   H₂N—C₃H₆—NH—CH₂—     -   H₂N—C₃H₆—NH—C₃H₆—NH—CH₂—     -   H₂N—C₂H₄—NH—C₃H₆—     -   H₂N—C₃H₆—NH—C₃H₆—     -   H₂N—C₂H₄—NH—C₂H₄—NH—C₃H₆—     -   H₂N—C₃H₆—NH—C₃H₆—NH—C₃H₆—     -   H₂N—C₂H₄—NH—C₄H₈—         R² is preferably a hydrogen atom.         R³ is particularly preferably an alkylene radical having 2 to 6         carbon atoms.         R⁴ is preferably a hydrogen atom.

Z preferably has a weight-based heteroatom content of at least 20% and particularly preferably at least 25%.

Preferred aminosilicon compounds (i) are organopoly-siloxanes having at least one Si—C-bonded radical A of the formula (VI).

Preferred aminosilicon compounds (i) are organopoly-siloxanes of the general formula

A_(g)R_(3-g)SiO(SiR₂O)_(l)(SiRAO)_(k)SiR_(3-g)A_(g)  (IXa),

(R′O )R₂SiO(SiR₂O)_(l)(SiRAO)_(k)SiR₂(OR′)  (IXb)

in which A has the meaning stated above therefor, R is a monovalent hydrocarbon radical having 1 to 18 C atoms, R′ is a hydrogen atom or a monovalent hydrocarbon radical having 1 to 18 C atoms, preferably a hydrogen atom, g is 0 or 1, k is 0 or an integer from 1 to 30 and l is 0 or an integer from 1 to 1000, with the proviso that at least one radical A is present per molecule.

Aminosilicon compounds (i) preferably contain amino group concentrations in the range of 0.01 to about 10 meq/g, in particular from about 0.05 to 5 meq/g. Preferred viscosities are in the range from about 100 to 50 000 mPa·s at 25° C., the range 500 to 10 000 mPa·s at 25° C. being particularly preferred.

The aminosilicon compounds (i) are preferably used without prior conversion of the amino groups by means of protective group reagents, such as aldehydes or ketones.

The aminosilicon compounds (i) are preferably prepared from “diamino” monomers, such as aminoethylamino-propyl- or aminoethylaminoisobutylsilanes, the Si—C— bonded amino group A containing both a primary and a secondary amino radical, bonded to the same Si atom. In the radicals A, preferably the primary amino radicals react with the compounds (ii), the secondary amino radicals being retained as basic centers.

The compounds (ii) can be used as reactants for the aminosilicon compound (i) in two tautomeric forms of the formulae (VIIa) and (VIIb).

The compounds (ii) are preferably obtained by reacting the parent compounds (iv) of the formula (E²)_(x)Z-Y (X), which are saturated with hydrogen at the free valencies,

in which E², Z, Y and x have the meanings stated above therefor, with diketenes, acetylketenes, alkyl-diketenes, diketene-acetone adducts or acetoacetates, preferably with diketenes or their acetone adducts, by methods known in the literature.

The radical “Z” is defined as an organic radical which, owing to its bifunctionality to hexafunctionality, is linked to 2 to 6 further groups E or Y: the sum of “E” plus “Y” corresponds in its numerical value to this bifunctionality to hexafunctionality. In the simplest case, which is also preferred, “Z” is bifunctional, i.e. divalent. In this case, “Z” is bonded either to two Y groups or to one Y group and one monofunctional terminal group. Monofunctional terminal groups may be saturated or unsaturated hydrocarbon radicals having 1 to 18 C atoms or acyl radicals, such as the acetate, butyrate, palmitate or stearate radical, as well as the acrylate, methacrylate or benzoate radical.

The radical “Z” has a heteroatom content of at least 10% by weight. Heteroatoms are selected from the group consisting of the O, N, B, P and S atoms; preferably O and N atoms, particularly preferably O atoms. The radical “Z” has the function of introducing higher polarity and hence a higher degree of hydrophilicity into the organosilicon compounds (1) according to the invention, and it is for this reason that a relatively high content of heteroatoms is preferred. The radical “Z” is particularly preferably a polyether or polyester. Examples of polyethers are polyethylene oxide, polypropylene oxide or polybutylene oxide (also poly-THF) and also copolymers of the general formula (C_(a)H_(2a)O)_(n)C_(a)H_(2a) where a=2, 3 or 4 and n is an integer from 1 to 500, preferably from 1 to 100 and particularly preferably from 5 to 60.

Trifunctional to hexafunctional radicals “Z” are usually started from alcohols of the same functionality as well as from amines. Thus, trimethylolpropane or ammonia gives, with ethylene oxide, parent compounds (iv) with “Z” of the general formula C₂H₅C[CH₂(OC₂H₄)_(m/3)]₃ or N [C₂H₄ (OC₂H₄)_((m-1)/3)]₃, in which m is the total number of moles of ethylene oxide, preferably 5 to 100, the free valencies of which are linked to oxygen atoms (Y) which in turn are saturated with hydrogen. For the preparation of parent compounds (iv) having a higher functionality, the correspondingly more highly functionalized carbinol or amino compounds are usually used: tetrafunctionality from pentaerythritol or ethylenediamine, hexa-functionality from sorbitol or tris(aminoethyl)amine.

Corresponding polyesters can be prepared from identical or similar starter compounds by ring-opening polymerization of cyclic esters (lactones) by generally known methods. Preferred parent compounds (iv) are polyethylene glycol, polypropylene glycol and the copolymers thereof, and the monoalkyl ethers thereof. The latter are a special case where “Y” is oxygen and “E” is an alkyl group (methyl, alkyl, butyl). With regard to the conversion into compounds (ii), these parent compounds (iv) are monofunctional. Compared with the aminosilicon compounds (i), the compounds (ii) prepared therefrom are likewise monofunctional and accordingly serve for saturating amino groups with polar polymers.

In contrast, bifunctional reactants (ii) which have a chain-extending effect with respect to likewise bifunctional aminosilicon compounds (i), i.e. which contain two amino groups A per molecule, are obtained from polyalkylene glycols. In this way, it is also possible to obtain branched products (2c) provided that the aminosilicon compounds (i) contain at least three amino groups A per molecule. An alternating siloxane-polyether structure forms.

The surprisingly high selectivity of the compounds (ii) having primary amino radicals in the amino groups A of the aminosilicon compounds (i) permits virtually complete conversion of the H₂N radicals into enamines, and it is for this reason that a stoichiometric ratio of primary NH₂ radicals in amino groups A of compounds (i) to acetoacetyl groups in compounds (ii) close to 1.0 is preferably used in the first stage of the method for the preparation of (2c). This ratio is particularly preferably 0.8 to 1.0. However, it may also be above 1.0. In this case, not all primary amino radicals are converted, which are then however additionally available for reaction with diketenes (iii). This procedure is technically possible but is not preferred.

In the method for the preparation of (2c), the acetone adducts of diketenes (iii) can also be used as said diketenes. Preferably used diketenes (iii) are

or their acetone adducts.

In the method for the preparation of (2c), the stoichiometric ratio of secondary —NH groups in amino groups A of compounds (i) to diketenes (iii) is 5:1 to 0.5:1, preferably 2:1 to 0.8:1, in the subsequent reaction with diketenes (iii). A ratio of about 1:1 is particularly preferred.

The method for the preparation (2c) can be effected in the presence of organic solvents or the products (2c) according to the invention can be diluted with organic solvents.

The reaction of the compounds (ii) with aminosilicon compounds (i) in the first stage of the method for the preparation of (2c) takes place spontaneously even without external heating but supply of heat accelerates the synthesis of (2c).

The method for the preparation of (2c) is preferably carried out at temperatures of 10 to 100° C., preferably 40 to 80° C. Furthermore, the method is preferably carried out at the pressure of the ambient atmosphere but can also be carried out at higher and lower pressures.

The treatment of the cellulose-containing fibers or planar structures containing cellulose-containing fibers can be effected in two different variants of the method.

In one variant of the method, the treatment of the cellulose-containing fibers or planar structures containing cellulose-containing fibers is effected preferably first with (1) compounds having at least two primary amino groups and subsequently with (2) compounds having at least one β-ketocarbonyl group.

The application of the compound (2) is effected only after the action of the compound (1) on the cellulose-containing fibers or planar structures containing cellulose-containing fibers.

In a second variant of the method, the treatment of the cellulose-containing fibers or planar structures containing cellulose-containing fibers is preferably effected with a mixture of (1) compounds having at least two primary amino groups and (2) compounds having at least one β-ketocarbonyl group, the mixture of (1) and (2) being prepared before the treatment. Thus, a premix of (1) and (2) is first prepared and the premix is then applied to the cellulose-containing fibers or planar structures containing cellulose-containing fibers.

In the method according to the invention, compounds (1) and (2) are used in amounts such that the compounds (1) are used in amounts of preferably 0.1 to 1000 mol, preferably 0.5 to 500 mol, particularly preferably 1.1 to 500 mol of amino group, based in each case on 1 mol of β-ketocarbonyl group in compounds (2).

Examples of cellulose-containing fibers which are treated according to the invention are all cellulose-containing fibers and all aqueous cellulose-containing slurries from which paper products can be produced, such as bleached fibers, recycled fibers, fibers which are produced via chemical digestion methods, such as the sulfate or sulfite method, fibers which are produced from vegetable raw materials (fibrous plants) and which have a sufficient cellulose content, and mechanical pulps which are produced predominantly by mechanical defibration of wood. The cellulose fiber-containing materials are materials such as wood, grass fibers, straw, bamboo, corn fibers and hemp, in each case in any desired forms, such as scraps, chips or sawdust.

Examples of planar structures containing cellulose-containing fibers are all paper products produced from cellulose-containing fibers, such as paper towels, toilet paper, tissues, kitchen paper, paper napkins, facial tissues.

The paper to be treated according to the invention may be low-quality paper varieties, such as absorptive papers, including base paper, i.e. kraft paper not pretreated with chemicals and/or polymeric natural substances having a weight of 60 to 150 g/m², unsized papers, paper having a low freeness, wood-containing papers, unglazed or uncalendered papers, papers which are smooth on one side owing to the use of a calendar stack in their production without further expensive measures and are therefore referred to as “papers machine-finished on one side”, uncoated papers and papers produced from paper waste, i.e. so-called waste papers. However, the paper to be treated according to the invention can of course also be high-quality paper varieties, such as low-absorption papers, sized papers, papers having a high freeness, wood-free papers, calendered or glazed papers, glassine papers, parchmentized papers or precoated papers. The boards may also be of high or low quality.

Preferably, the compounds (1) and (2) are used in the form of aqueous solutions or aqueous dispersions in the treatment of the cellulose-containing fibers or planar structures containing cellulose-containing fibers. In the aqueous solutions or aqueous dispersions, compound (1) is preferably present in amounts of 0.1 to 20% by weight, preferably 0.2 to 10% by weight.

In the aqueous solutions or aqueous dispersions, compound (2) is preferably present in amounts of 0.1 to 50% by weight, preferably 0.5 to 20% by weight.

The treatment of cellulose-containing fibers or planar structures containing cellulose-containing fibers can be effected by the methods known in the prior art, in particular by the methods known in the production and finishing of paper products, as described, for example, in U.S. Pat. No. 6,824,650 B2, column 12, line 1 to column 13, line 15.

The production of paper products as treated according to the invention is described in U.S. Pat. No. 6,824,650 B2, column 15, line 20 to column 19, line 11.

Some possible treatments are mentioned by way of example:

The treatment can be effected by metering the compounds (1) and (2)—either individually in successive steps or together as a premix of (1) and (2)—into the aqueous cellulose-containing fiber slurry from which the planar structures containing cellulose-containing fibers, such as paper products, are produced or during the concentration or drying process.

The treatment can also be effected by spraying the compounds (1) and (2)—either individually in successive spraying steps or together as a premix of (1) and (2)—onto the planar structures containing cellulose-containing fibers, such as paper products. The planar structures may be moist or dry during the process.

The treatment can also be effected by coating the surface of the planar structures, such as paper products, with the compounds (1) and (2)—either individually in successive steps or together as a premix of (1) and (2).

The treatment can also be effected by impregnating the wet or dry planar structures with the compounds (1) and (2)—either individually in successive steps or together as a premix of (1) and (2)—the planar structures being completely or partly penetrated therewith.

The invention furthermore relates to paper products containing

planar structures containing cellulose-containing fibers, the planar structures furthermore containing a combination of

-   (1) compounds having at least two primary amino groups and -   (2) compounds having at least one β-ketocarbonyl group.

The compound (1) and (2) are preferably added to cellulose-containing fiber slurries which are used for the production of the planar structures.

The compounds (1) and (2) are preferably used in each case in amounts of 0.1 to 50% by weight, preferably 0.2 to 20% by weight, based on the total weight of the dry cellulose-containing fibers or dry planar structures containing cellulose-containing fibers.

In addition to the compounds (1) and (2), further substances which are usually concomitantly used in the treatment of cellulose-containing fibers or planar structures containing cellulose-containing fibers can also be concomitantly used. An example of further substances are antifoams, dry strength agents, such as (modified) starch, carboxymethylcellulose or (modified) polyacrylamides, softening agents, drainage aids or retention aids.

The treatment according to the invention is preferably carried out at temperatures of 5 to 60° C., preferably 15 to 35° C. The treatment according to the invention is preferably carried out at the pressure of the ambient atmosphere, i.e. at 1020 hPa, but can also be carried out at higher or lower pressures.

EXAMPLES Compound (I)

All tests relate to the combination of (1) with various compounds (2). Exclusively Lupamin 9095 (BASF), a high molecular weight polyvinylformamide having a degree of hydrolysis of about 95% and an amino group concentration of about 3.8 meq/g for the 20% strength aqueous solution (commercial product) was used as compound (1).

Preparation Examples for the Compound (2) Example 1

73.1 g of N,N,N,N-tetrakis(2-hydroxypropyl)ethylene-diamine are heated to 50° C. Thereafter, 92 g of diketene are metered in with cooling so that the temperature of the reaction mixture is kept between 50 and 70° C. The reaction is allowed to continue for a further hour and excess diketene is removed in vacuo at 100° C. A pale orange product having an acetoacetate content of 6.3 meq/g is obtained.

Example 2

250.5 g of a trimethylsilyl-terminated aminosiloxane which contains dimethylsilyloxy and aminoethylamino-propylmethylsilyloxy units and has a concentration of 2.24% by weight of basic nitrogen are mixed with 411.4 g of a polyether acetyl acetate of the average formula CH₃O(C₂H₄O)_(19.4)(C₃H₆O)_(17.1)C(═O)—CH₂C(═O)—CH₃ and heated to 70° C. On clarification, the viscosity of the reaction mixture increases sharply, whereupon 70 g of isopropanol are metered in. At 70° C., 16.8 g of diketene are slowly added dropwise, followed by altogether a further 156 g of isopropanol after a further hour. The high-viscosity product has a solids content of 75% and an acetoacetamide content of 0.22 meq/g.

Example 3

400 g of 75% strength solution obtained in example 2 are homogeneously mixed with 0.75 g of isophoronediamine at 25° C. and slowly heated to 40° C. With a considerable increase in viscosity, a clear, high-viscosity polymer solution having an acetoacetamide content of 0.20 meq/g is obtained in 2 hours.

Example 4

13.3 g of the 75% strength solution obtained in example 2 are homogeneously mixed with 10.0 g of the diacetoacetate of PEG 1000 and diluted with isopropanol to 200 g. The clear solution contains 0.105 meq/g of β-ketocarbonyl groups per g.

Example 5

0.1 g of triethylamine and thereafter 20.6 g of diketene are slowly metered into 200 g of a silicone polyether prepared from 2 parts of allylpolyether of the formula CH₂═CH—CH₂O(C₂H₄O)₁₀H and 1 part of hydrogen-siloxane of the formula HO(HSiMeO)_(14.3)(SiMe₂O)₆₀H. After an exothermic reaction, the batch is kept at 70° C. for a further hour. A pale brownish product which has a viscosity of about 20 000 mm²/s in undiluted form is obtained. The concentration of acetoacetate is 1.10 meq/g.

Example 6

50 g of the polymeric acetoacetate obtained in example 5 are further condensed at 100° C. after dropwise addition of 0.2 g of a 10% strength solution of p-toluenesulfonic acid in THF, with the result that a gel-like high polymer which is soluble in the same amount of isopropanol to give a clear solution is obtained. The 50% strength solution contains aceto-acetate groups at a level of 0.55 meq/g.

Example 7

By dilution of a commercially available aqueous solution (Lupamin 9095, BASF) of a high molecular weight polyvinylamine (about 19 meq of NH₂ per g) with the same amount of water, a 10% strength solution is prepared. 6.0 g of a 10% strength aqueous solution of the diacetoacetate of PEG 2000 are added to 200 g of this dilution and homogeneously mixed. After 3 days, a clear aqueous solution which no longer contains detectable acetoacetate is obtained. The mixture is a ready-to-use one-component formulation of the compounds (1) and (2). The molar ratio of amino to acetoacetate groups is about 700:1.

Example 8

For the preparation of a 10% strength aqueous solution of the combination of compounds (1) with an exclusively monofunctional compound (2), 24 g of Lupamin 9095 (BASF), 67.2 g of water and 4.8 g of ethyl acetoacetate are mixed in succession. A clear colorless mixture is obtained, to which 0.65 g of acetic acid is added after 24 hours. The mixing ratio of amino to acetoacetate groups is about 2.5:1.

Example 9 Dry and Wet Strength Tests

The dry and wet strength of paper towels is tested.

Regardless of the preparation process, all examples of the compounds (2) are used as a 10% strength aqueous solution. This also applies to the one-component formulation of examples 7 and 8.

In the case of two-component applications, the polyamine (1) is in principle applied first as a 1% strength aqueous solution by the spray process described below and is dried at 105° C. for 5 minutes. The active substance application of compound (1) is stated in the table and is 0.5 or 0.9% by weight, based on the dry weight of the paper towel.

The substrate, the paper towel, is preconditioned therewith.

The specified paper towel having a very low tensile strength is cut to a size of 1×w=15×35 cm. This is placed without creases in a vertical clamping apparatus and sprayed uniformly (3×per sheet of paper towel) from top to bottom using a Sata 200 Dekor spray gun. The settings on the spray gun always remain the same and are 2 bar compressed air with a spray nozzle of 0.5 mm. Depending on amount of product and type, this process is repeated until 4.8-5.2% by weight of active product (=compound (2)) is present on the paper towel. In the table, the active substance application of compound (2) is stated in % by weight, based on the dry weight of the paper towel. This product application is determined by weighing the uncoated and the wet paper towel. The product application is effected on one side. Thereafter, the coated paper towel is dried at 105° C. for 5 min.

TABLE Test results of the testing of dry and wet strength of paper towels Compound (2) Polyamine Soft TEA TEA (2) in %* (1) in %* handle (wet) (dry) Example 1 4.9 0.5 − 11 42 Example 2 5.0 0.9 + 11 32 Example 3 4.8 0.5 + 9 32 Example 4 5.0 0.5 + 7 Example 5 5.0 0.5 + 6 23 Example 6 5.1 0.5 + 7 29 Comparison — 0.5 −− 6 42 1 Comparison — 0.9 −− 9 2 Blank — — 0 2 31 sample Example 7** 0.02 0.5 − 8 46 Example 8** 0.5 0.5 − 8 50 *The active substance application is stated in % by weight, based on the dry weight of the paper web. **Polyamine (1) and compound (2) applied premixed. The soft handle was assessed as softer (+) or harder (− or −−) than the blank sample.

Description of the dry breaking strength (cf. DIN EN 29 073 part 3 or ISO 9073-3):

The paper towel to be tested is cut into at least 10 strips having a minimum length of 152 mm and a width of 25 mm in the running direction.

Five test specimens thereof are used for measuring the dry breaking strength and 5 for the wet strength.

The test specimens are clamped in the ZWICK 1446 tensile tester, likewise in the running direction, and the following parameters are set:

traction speed=0.21 mm/s (12.7 mm/min) sample length=152 mm (6 inches)

By starting the tester, the force in F-Max [N or g/force], the elongation at F-max [%] and the resulting area (load-elongation curve) TEA or energy up to breaking in [J] are recorded.

By inputting the weight, it is also possible to determine the tensile force per tex in cn/tex. This process is repeated at least 5 times and the mean value and standard deviation of each parameter is determined.

Description of the wet breaking strength (cf. DIN ISO 3781):

In the measurement of the wet breaking strength, the paper towel is moistened in the middle by brief immersion in demineralized water to at least 25 mm to not more than 50 mm. The ends remain dry for clamping. (Cf. also point 8.2 in DIN ISO 3781.) The evaluation and settings are the same as for the dry breaking strength method.

The energy (in Joule) absorbed by the test strips was compared with the blank sample (TEA=2) and the strips treated only with polyamine (1) (TEA=6 and 9), comparative experiments 1 and 2, respectively. The improvement in the wet strength of the test strips by the additional compound (2) is clear from the higher TEA values, with improved soft handle throughout in the comparison with the test strips treated only with (1). In most cases, even an improvement in the soft handle compared with the blank sample is achieved.

All test strips proved to be hydrophilic with drop absorption times of less than two seconds. 

1.-18. (canceled)
 19. A method for treating a substrate of cellulose-containing fibers or planar structures containing cellulose-containing fibers, comprising treating with a combination of (1) compounds having at least two primary amino groups and (2) compounds having at least one β-ketocarbonyl group.
 20. The method of claim 19, wherein the compounds (2) contain β-ketocarbonyl groups of the formula —Y′—C(O)—CHR⁴—C(O)—CH₂R⁴ or their tautomeric enol form of the formula —Y′—C(O)—CR⁴═C(CH₂R⁴)—OH in which Y′ is —O—, —NR²— or

R² is a hydrogen atom or a monovalent hydrocarbon radical having 1 to 30 C atoms, and R⁴ is a hydrogen atom or a monovalent hydrocarbon radical having 1 to 18 C atoms.
 21. The method of claim 19, wherein Y′ is —O—.
 22. The method of claim 19, wherein one or both of R² and R³ are hydrogen.
 23. The method of claim 19, wherein polyamine(s) are used as at least one compound (1).
 24. The method of claim 19, wherein β-ketocarbonyl-functional monomeric compounds (2a) of the formula L(—Y—C(O)—CHR⁴—C(O)—CH₂R⁴)_(e)  (I) or their tautomeric enol forms in which e is an integer from 1 to 20, L is a monomeric organic radical having the valency or functionality corresponding to the index e in formula (I), and Y is —O— or —NR²—, R² is a hydrogen atom or a monovalent hydrocarbon radical having 1 to 30 C atoms, and R⁴ is a hydrogen atom or a monovalent hydrocarbon radical having 1 to 18 C atoms, are used as compounds (2).
 25. The method of claim 24, wherein e is 2 to
 8. 26. The method of claim 19, wherein β-ketocarbonyl-functional oligomeric or polymeric compounds (2b) of the formula K(—Y—C(O)—CHR⁴—C(O)—CH₂R⁴)_(f)  (III) or their tautomeric enol forms, in which f is an integer from 1 to 10,000, K is an oligomeric or polymeric, organic or organosilicon radical having the valency or functionality corresponding to the index f in formula (III), and Y is —O— or —NR²—, and R⁴ is a hydrogen atom or a monovalent hydrocarbon radical having 1 to 18 C atoms, are used as compounds (2).
 27. The method of claim 26, wherein an organopolysiloxane radical or an organopolysiloxane-containing copolymer radical is a radical K in the β-ketocarbonyl-functional oligomeric or polymeric compounds (2b).
 28. The method of claim 19, wherein β-ketocarbonyl-functional organosilicon compounds (2c) which contain at least one Si-bonded radical of the general formula

in which —(Si≡) is the bond to the silicon atom, R¹ is a divalent organic radical having 1 to 6 carbon atoms which optionally contain non-adjacent nitrogen atoms, R³ is a divalent organic radical having 1 to 6 carbon atoms, Y is —O— or —NR²—, R² is a hydrogen atom or a monovalent hydrocarbon radical having 1 to 30 C atoms, and R⁴ is a hydrogen atom or a monovalent hydrocarbon radical having 1 to 18 C atoms, Z is a divalent to hexavalent organic radical having a monomeric, oligomeric or polymeric structure, which has a weight-based heteroatom content of at least 10%, which is bonded via C atoms, E¹ is a monofunctional terminal group or an Si—C-bonded radical of the formula

a is an integer from 1 to 5, and x is 0 or an integer from 1 to 5, are used as compounds (2).
 29. The method of claim 28, wherein Z is a polyether or polyester radical.
 30. The method of claim 19, wherein the treatment of the substrate is effected first with (1) compounds having at least two primary amino groups and subsequently with (2) compounds having at least one β-ketocarbonyl group.
 31. The method of claim 19, wherein the treatment of the substrate is effected with a mixture of (1) compounds having at least two primary amino groups and (2) compounds having at least one β-ketocarbonyl group, the mixture of (1) and (2) being prepared before the treatment.
 32. The method of claim 19, wherein the compounds (1) are used in amounts of 1.1 to 500 mol of amino group per mole of β-ketocarbonyl group in compounds (2).
 33. The method of claim 19, wherein as the compounds (1) and (2) are used in the form of aqueous solutions or aqueous dispersions.
 34. The method of claim 19, wherein aqueous cellulose-containing fiber slurries are used as cellulose-containing fibers.
 35. The method of claim 34, wherein the compounds (1) and (2) are added to the aqueous cellulose-containing fiber slurries, the compounds (1) and (2) being added (i) either individually in successive steps or (ii) together as a premix of (1) and (2).
 36. The method of claim 19, wherein paper products, such as paper towels, are used as planar structures containing cellulose-containing fibers.
 37. The method of claim 36, wherein paper towels are the planar structures.
 38. The method of claim 36, wherein the compounds (1) and (2) are sprayed onto the paper products, the compounds (1) and (2) being sprayed on (i) either individually in successive spraying steps or (ii) together as a premix of (1) and (2).
 39. A paper product containing planar structures containing cellulose-containing fibers, the planar structures furthermore containing a combination of (1) compounds having at least two primary amino groups and (2) compounds having at least one β-ketocarbonyl group.
 40. The paper product of claim 38, wherein the compounds (1) and (2) are added to aqueous cellulose-containing fiber slurries which are used for producing the planar structures. 